In the technical field of TFT-LCD (Thin Film Transistor-Liquid Crystal Display), in the OLB (Outer Lead Bonding) projection ultraviolet light coating process, in order to achieve the purposes of preventing the lead from being corroded due to the electrodes after bonding being exposed in the air and avoid light leakage, three processes including a front coating process, a back coating process and a side sealing process are mainly included. The back coating process and the side sealing process can be selectively performed according to the product design and the requirements of customers, and the front coating process is performed to the products of all types. In order to apply three different coating processes, the currently used UV coating apparatus is respectively designed with three coating units, respectively including a front coating unit, a back coating unit, and a side sealing unit, and each of the units respectively use 1-2 coater(s) to perform the coating process.